我在NSManagedObjectContext类中有一个简单的函数来帮助我从我的moc中获得结果。我正在执行moc实例提供的performBlockAndWait块内的结果。我需要返回一个autoreleased数组,并且通常来自moc的executeFetch已经完成了这个。但在这种情况下,即使我用__block指令声明了数组,我仍然需要在块内部保留数组。它看起来像块一旦完成就释放出来。 这是正常的吗? 谢谢。了解块中的变量(__block指令)
-(NSArray*)executeFetchWithEntityName:(NSString*)entityName predicate:(NSPredicate*)predicate{
NSEntityDescription *entity = [NSEntityDescription entityForName:entityName inManagedObjectContext:self];
if (!entity) {
NSLog(@"entity is nil in executeFetchWithEntityName: %@", entityName);
return [[[NSArray alloc]init]autorelease];
}
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc]init];
[fetchRequest setEntity:entity];
if(predicate){
[fetchRequest setPredicate:predicate];
}
__block NSError *error = nil;
__block NSArray *array = nil;
[self performBlockAndWait:^{
array = [self executeFetchRequest:fetchRequest error:&error];
[array retain]; <------ IF I DONT RETAIN HERE, IT CRASHES FURTHER ON
}];
NSLog(@"retain count: %i", array.retainCount);
if (error) {
NSLog(@"error");
array = nil;
}
[fetchRequest release];
return [array autorelease];
}
Re。您使用retainCount:http://www.whentouseretaincount.com/ – 2012-03-15 17:19:18
@StephenDarlington - 最后!一个明确的参考链接! – jrturton 2012-03-15 17:30:27
jajaja excellent – 2012-03-15 17:45:25